Various types of catalyst structures formed by combining a catalyst metal and an inorganic fiber substrate are known, and are used in various applications for purification of exhaust gas, production of chemical products, etc.
JP-A-2009-255047 describes a honeycomb structure carrying a catalyst, in which the amount of the carried catalyst is from 100 to 400 g/L, and which has, in the Log differential pore size distribution curve relating to the pore size distribution according to a mercury intrusion technique, there are three peaks in a range of from 0.005 to 0.03 μm, in a range of from 1 to 15 μm and in a range of from 15 to 30 μm, respectively.
JP-A-2005-052750 describes a ceramic honeycomb catalyst for exhaust gas purification systems having a catalyst substance carried on a ceramic honeycomb structure, wherein the mean micropore diameter in partitions of the ceramic honeycomb structure is 15 μm or more, and the porosity in the partitions is from 50 to 80%.
JP-A-2008-545533 describes a catalyst containing silver carried on a support, wherein the support has micropores having a surface area of at least 1.3 m2/g and a median micropore diameter of more than 0.8 μm, and having a pore size distribution such that micropores having a diameter within a range of from 0.1 to 10 μm account for at least 80% of the entire micropore volume, and micropores having a diameter within a range of from 0.3 to 10 μm account for at least 80% of the total micropore volume of the micropores having a diameter within a range of from 0.1 to 10 μm. Those containing alumina as the support are described (claim 6, etc.).
Various catalyst structures having catalyst metal particles carried on a porous support are known, and some methods are known as production methods for them. For example, JP-B-4974757 describes producing a particles-carrying porous material by impregnating a porous material with a dispersion of particles, then rapidly cooling it to freeze water in voids thereof, and thereafter heating and drying it. JP-A-2011-132626 describes a technique of applying a photocatalyst dispersion to a fluffed fibrous cloth and drying it to enable the photocatalyst to be carried on the surface of the fibrous cloth. JP-A-2002-326036 discloses a technique of immersing an inorganic fibrous structure in an aqueous solution containing an active component element-having organic acid salt, a surfactant and a solvent, and drying and calcination the structure.